The latest on the massive trail derail nmt new york. This is a live scene. At the disaster scene outside the bronx. Cranes have begun to lift the cars back on to the tracks. Gio bennett teitez is on the scene. Reporter: There you see it live. Those cranes hard at work. So are investigators. Abc news has learned that investigators will know today how fast this train was going and whether those brakes worked. Overnight, cranes turned over the cars of the train. The ntsb tweeting these photos of investigators retrieving the important black boxes. The data may tell us what happened. James ferrari, 54-year-old donna smith, 35-year-old kisook ahn, and 58-year-old james lovell, going in to work on the christmas tree at rockefeller ept center. This picture reportedly shows passengers standing inside a flipped over car. And this new video shows the scene of the metro north crash from a passing train. Our submission to understand not just what happened but why it happened. Reporter: The train's engineer, william rockefeller jr. Said he applied the brakes but they didn't work. He's a 20-year veteran with a clean disciplinary record. The plane left poughkeepsie at 5:54 a.M. Sunday. Nearly an hour and half later, at 7:20, as the train reached this curve, the massive derailment. Ryan kelly survived the crash. Everyone around me was all right, except one woman pinned between two feets. Reporter: This acdent happened in almost the same spot are a train derailed in july. For people who use the train every day, what do you say to them? The systems are safe. Just based on sheer volume, sometimes accidents happen. In terms of the cause here, that has to be determined by a full investigation. Reporter: This morning, we know that investigators will interview the train's engineer. Sadlhese are the first deaths on a metro north train in the agency's 31-year history, robin. Thank you, g iio. We're thinking of the families that are affected. Including our friends at nbc suffering the loss. We're going turn to the

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